1992/10/01 by Vernard R. Lewis
Environmental Science · #Animal Ecology and Behavior Studies #Ecology and Vegetation Dynamics Studies #Forest Insect Ecology and Management
paper · doi:10.1093/ee/21.5.975
openalex publication_date 1992/10/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/25
Terminal shoots from coast live oaks, Quercus agrifolia Nee, were sampled to determine the abundance and spatial distribution of acorns infested by the filbert weevil, Curculio occidentis (Casey), and the filbertworm, Cydia latiferreana (Walsingham), at a site in northern California during 1989. Nine sampling strata in the tree crown were vertically aligned into blocks of three, each facing a different compass direction (NE, S, and NW). Overall, 25% of all acorns examined on shoots of sample trees revealed signs of insect-boring activity. Acorn numbers were most abundant in May and logarithmically declined throughout the season. The frequency of insect-infested acorns on shoots during the season resembled a random distribution; however, this resemblance was not significant. Peak numbers of infested acorns appeared in mid-September. Within crowns, most acorns occurred in sampling strata within the south-facing section. Significantly more infested acorns occurred in sampling strata within the northeasterly and south-facing sections of the crown. Dissection of 501 acorns revealed infestation rates of 38%. Of those acorns found to contain insect larvae, 66% contained C. occidentis and 27% contained C. latiferreana . Possible mechanisms for explaining the dissimilar distribution of total and infested acorns within crown strata are discussed. The implications of these findings to the development of sampling schemes for ecological studies of acorn and acorn-boring insects are also discussed.